The present invention relates to an improvement in a non-aqueous electrochemical cell.
A non-aqueous electrochemical cell using lithium or sodium as an active anode material has high energy density, good storage characteristics, and wide operation temperature range. A non-aqueous electrochemical cell is therefore often used as a power source for a calculator, a watch, or a memory back up system. Such a cell comprises an anode, an electrolyte and a cathode. In general, such a cell uses as an anode an alkali metal such as lithium or sodium; as an electrolyte or electrolytic solution, a solution of a solute such as lithium perchlorate or lithium tetrafluoroborate in a non-aqueous solvent such as propylene carbonate, .gamma.-butyrolactone, or dimethoxyethane; and as a cathode, manganese dioxide or poly-carbonmonofluoride.
Among such cells, a cell using thionyl chloride as a main active cathode material is receiving a lot of attention due to its high energy density. A cell of this type has a cathode consisting of a porous carbon body and a current collector and has an electrolyte, a solution of lithium chloride (LiCl) and aluminum chloride (AlCl.sub.3) in thionyl chloride (SOCl.sub.2). Therefore, SOCl.sub.2 serves both as the main active cathode material and as the solvent for the electrolyte salt.
In a cell using SOCl.sub.2 as an active cathode material, the anode reaction is the reaction in which the anode metal is dissolved in the electrolyte as metal ions. On the other hand, the cathode reaction occurs on the porous carbon body as one constituent member of the cathode, and the reaction product of the cathode reaction is deposited on the porous carbon body. However, in a conventional cell having a cathode comprising a porous carbon body which is obtained by mixing acetylene black with a polymer binder such as polytetrafluoroethylene, forming a resultant mixture into a predetermined shape, and drying the formed body upon deposition of the reaction product on the porous carbon body, the electrode reaction is significantly interfered with and the discharge capacity is lowered. Especially, the discharge efficiency is considerably lowered in a high rate discharge as compared to a low rate discharge.